In an information recording medium, such as a CD-ROM (Compact Disc-Read Only Memory), a CD-R (Compact Disc-Recordable) and a DVD-ROM, for example, as described in patent documents 1 and 2, etc., there is also developed an information recording medium, such as a multi-layer type optical disc, in which a plurality of recording layers are laminated or pasted on the same substrate. Then, on an information recording apparatus, such as a DVD recorder, for performing the recording with respect to the dual-layer type (i.e., two-layer type) optical disc, laser light for recording is focused on a recording layer located on the front (i.e. on the closer side to an optical pickup) as viewed from the irradiation side of the laser light (hereinafter referred to as an “L0 layer”, as occasion demands) to thereby record data into the L0 layer in an irreversible change recording method or a rewritable method by heat. Moreover, the laser light is focused or condensed on a recording layer located on the rear of the L0 layer (i.e. on the farther side from the optical pickup) as viewed from the irradiation side of the laser light (hereinafter referred to as an “L1 layer”, as occasion demands), through the L0 layer or the like, to thereby record information into the L1 layer in the irreversible change recording method or the rewritable method by heat.    patent document 1: Japanese Patent Application Laid Open No. 2000-311346    patent document 2: Japanese Patent Application Laid Open No. 2001-23237